Artificial leg having a knee joint construction which selectively permits either manual or automatic rotation between the stump unit and lower leg unit



Nov. 14, 1967- I I F. MIDDLETON R 3,351,955

ARTIFICIAL LEG HAVING A KNEE JOINT CONSTRUCTION WHICH SELECTIVELYPERMITS EITHER MANUAL 0R AUTOMATIC ROTATION BETWEEN THE STUMP UNIT ANDLOWER LEG UNIT Filed Dec. 30, 1964 2 Sheets-Sheet 1 INVENTOR.

46 v FRANK M/DDLETO/V ATTORNEYS 14, 1967 F. MIDDLETON ARTIFICIAL LEGHAVING A KNEE JOINT CONSTRUCTION WHICH SELECTIVELY PERMITS EITHER MANUALOR AUTOMATIC ROTATION BETWEEN THE STUMP UNIT AND LOWER LEG UNIT FiledDe. so. 1964 2 Sheets-Sheet 2 N m R ATTORNEYS United States Patent3,351,255 ARTIFICIAL LEG HAVING A KNEE JOINT CON- STRUCTIGN WHICHSELECTIVELY PERMITS EITHER MANUAL 0R AUTOMATIC ROTATION THE TUMP UNITAND LGWER LEG Frank Middleton, 2918 Westport Road, Lexington Park,Peoria, II]. 61614 Filed Dec. 30, 1964, Ser. No. 422,179 6 Claims. (Cl.3-22) ABSTRACT OF THE DISCLQSURE In an artificial leg having a stumpunit for receiving the remaining portion of the wearers thigh and anarticulating lower leg portion connected to the stump unit through ahinged swingable knee joint, a rotatable assembly associated with kneejoint which allows the leg portion to rotate relative to the stump unit,after the joint has been flexed a preselected amount, with accompanyinglock and release means operated by the flexing movement between thestump unit and the lower leg portion.

In attempting to incorporate mechanisms operating to duplicate themotion and the freedom of movement inherent in a natural leg, varioustypes of structures incorporating purely mechanical and hydro-mechanicaldevices have been developed. Although prior art devices have beensuccessful in solving many problems of controlled articulation, problemsare encountered by the wearer in achieving a sitting position in whichstrain is relieved and in permitting a stable position when it isdesired to put on or remove socks, shoes, and trousers.

The present invention discloses a new and improved knee joint which notonly permits the wearer to overcome the above difficulty but also isconstructed and arranged so that one may assume a cross-legged positionon the floor or allow the wearer to rotate the stump unit relative tothe leg unit which is particularly desirable during athletic activities,such as golf, and thereby enabling the wearer to achieve a full pivot onthe swing.

An ever-present and critical hazard to the wearer is presented in theevent of a fall. If the leg should remain rigid or substantially rigid,during a fall, the chances of producing a hip fracture or other seriousdamage to the body is greatly increased. The knee joint of thisinvention automatically conditions the knee joint to permitsubstantially unlimited transverse rotation of the leg unit about thelongitudinal axis of the stump unit and thereby decreases the chances offracturing or damaging the hip joint.

Accordingly, it is an object of this invention to provide a new andimproved knee joint for an artificial leg.

Another object of this invention is to provide a new and improved kneejoint adapted to permit lateral movement of the leg unit relative to thestump unit when the knee is bent a predetermined amount.

A further object of this invention is to provide selectively operablemeans permitting the leg unit to rotate relative to the stump unit.

Another and further object of this invention is to provide a new andimproved knee joint being adapted for automatically conditioning the legunit to rotate in a transverse direction relative to the stump unit inorder to facilitate placement or removal of a shoe or sock from theartificial foot.

The foregoing and other objects and advantages, of the present inventionwill become apparent to those skilled in the art upon consideration ofthe following detailed description of the preferred embodiment thereof,

3,351,955 Patented Nov. 14, 1967 reference being had to the accompanyingsheet of drawings wherein:

FIG. 1 is a side elevation, partly in section, of a knee jointconstructed in accordance with the principles of this invention.

FIG. 2 is similar to FIG. 1 but showing the leg unit rotated at leastwith respect to the stump unit.

FIG. 3 is a transverse section taken substantially along the lineIII-III of FIG. 1.

FIG. 4 is a transverse section taken substantially along line IVIV ofFIG. 1.

FIG. 5 is a longitudinal section of a modified form of the knee joint ofthis invention incorporating a knee release mechanism of simplifiedconstruction.

FIG. 6 is a transverse section of FIG. 5 taken substantially along theline VIVI.

FIG. 7 is a perspective showing the constructional details of the manualrelease mechanism.

FIG. 8 is a front elevation of FIG. 6 with the knee cap removed.

FIG. 9 illustrates the position assumed by the manual knee releasemechanism when it is positioned to allow rotation of the knee.

Referring now to the drawings, the novel artificial leg constructed inaccordance with the principles of this invention is generally indicatedby the numeral 10 and includes a stump unit or socket 12, a leg unit 14,and a knee joint 16. The knee joint 16 is constructed and arranged topermit transverse rotation of the leg unit relative to the longitudinalaxis of the stump unit.

In accordance with the basic feature of this invention, the knee joint16 is provided with means, indicated by the numeral 18, which isarranged to allow the stump socket to be automatically or manuallyselectively operated in order to enable the leg unit to rotate about itslongitudinal axis relative to the stump unit. Such means comprise asaddle member 20 which is generally circular in configuration andincludes projecting ear portions 22 which have axially aligned bores forreceiving a transverse shaft 24. The shaft is positively retained inposition by set screws 22a in the ear portions. Leg support members 26are joined together with a cross tube 28. This cross tube containsbushing bearings which support and space the leg assembly and allowrotation on the transverse shaft 24. Solidly fixed midway on the crosstube 28 is a cam member 30. Located rearwardly and between the legmembers 26 is an additional leg member 32 which is mounted for pivotalmovement between projecting cheeks 34 through which extends a shortpivot shaft 36. As is known to those skilled in the art, the leg members26 and 32 are associated with hydraulic devices (not shown) whosefunction is to control the action or movement of the leg unit relativeto the stump unit during normal walking.

The saddle member 20 is secured, by means of a plurality ofcircumferentially spaced screws 38', to a generally spherical knee cap40 which is suitably slotted (FIG. 3) at 42, 44 and 46 to accommodatethe leg members 26 and 32 when the leg unit is rotated about the shaft24. As shown in FIGS. 1 and 2 the saddle member 20 includes a threadedbore 48 within which is threadedly mounted an annular ring member 50secured to the lower end of the stump unit by a plurality of screws 52.As shown in FIG. 4, a lock bar 54 is located within the bore of the ringmember 50 and has the end thereof formed to be received within a keyslot 56 provided on the ring 50. The lock bar 54 is associated withresilient means for urging it into the key slot 56 and such meanspreferably comprises a spring 58 in contact with a portion of the innerperiphery of the ring 50 and having an inwardly extending end portion 57secured to the lock bar by a screw 60. It will be apparent that the lockbar 54 can be withdrawn from the key slot 3 by imparting a force againstthe tension of the spring 5&

The saddle member is provided with a rectangular opening 61 such thatwhen the ring member is in as semb le'd relation with the saddle 20 aportion of the lock bar 54 extends through the slot and has attachedthereto, by means of fasteners 64, a generally L-shaped lock baractuator 66. This actuator comprises a leg portion 63 projectinggenerally normal to the surface of the saddle member 20 and ismaintained in contact with the surface of the cam 30. By thisarrangement, when the leg unit is rotated about the axis of the shaft24, as shown in FIG. 2, the lobe 70 of the cam member .36 engages theleg 68 causing the lock bar 54, which is attached to the lock baractuator 66, to be withdrawn from the key slot 56 against the bias ofthe spring 58 permitting relative rotation betsvgeen the saddle member24) and the annular ring member Thus it is seen that this inventionprovides a pair of relatively rotating members which are normally heldagainst rotation with means provided therewith being operable, when theleg unit assumes an orientation of approximately 90 with respect to thestump unit, for allowing rotation between the two members.

In order to adjust the relative freedom of rotation between the saddlemember 241 and the annular ring member 50, the saddle member is slottedat 72 and provided with an undercut of a milled flat 74. An adjustmentscrew 76 having its head seated against the flat '74 is threaded intothe tapped portion '78 of a bore 80. It is apparent that upon tighteningof the screw 76 the threaded portion of the saddle 20 experiences aslight reduction in diameter which accordingly results in a closer fitfor the threads on the ring 50.

According to another feature of this invention manually operable meansare provided for permitting relative rotation between the ring member 50and the saddle member 20'. Such means are generally indicated by thenumeral 81 and comprise a cylindrical plunger 82 having a head portion84 extending through a blended fillet 86 defining a transition surfacebetween the stump unit and the knee joint. The cylindrical plunger 82extends through a guide bushing attached to or part of the knee cap 41Its inner end is aligned with the end surface of the lock bar actuator66 and the lock 'bar spring maintains the plunger in the retractedposition. It will be noted that when the plunger is depressed by thewearer against the bias of the lock bar spring, it displaces the lockbar 54 from the key slot 56, allowing relative motion between saddlemember 20 and the ring 50. According to the above construction, it isapparent that to maintain the lock bar out of the key slot 56, a slightamount of rotation of the plunger 82 will lock the end lip at the end ofthe lock bar guide slot 61 in the saddle member 20. If it is desired tomaintain the lock bar out of engagement with the key 56, a latch ordetent mechanism can be incorporated with the plunger 82 holding theplunger in its depressed position.

Thus, according to this invention, a very simple and dependableapparatus is provided in which two relatively rotating members 20 and50, one of which is rigid with the leg unit and the other rigid with thestump unit, may be operated so that upon bending of the artificial leg apredetermined amount the relatively rotatable members are conditioned topermit rotation of the leg unit relative to the stump unit.

The embodiment of the invention shown in FIGS. 5-9 fulfills the samefunction of allowing automatic or manual rotation of the stump unit 12relative to the leg unit 14. In fulfilling these functions, the modifiedconstruction eliminates the need of the lock bar 54 and its associatedspring 58 resulting in a simplified construction.

Referring now to FIGS. 5, 6 and 7, wherein like numerals refer tocorresponding structure described in connection with FIGS. 1-4, it willbe seen that the saddle member 20 is formed to provide a solid wall 100on the 4 surface of which is situated the lock bar actuator 66. Upwardlyextending transversely aligned posts 102, integral with the saddlemember 20, have generally L-shaped leaf springs 194 attached thereto bycap screws 106, and as seen most clearly in FIGS. 6 and 7, the innerends of these springs are overlapped and extend through a clearance slot108 formed in an enlarged end 110 of the lock bar actuator 66. Theportion of each leaf spring 194 extending through the clearance slot 108is of suflicient length to be received inthe key slot 56 of the annularring 50. While in the position shown in FIG. 5, relative rotationbetween the saddle member 20 and the annular ring 50 is prevented.

When the wearer of the artificial leg sits down causing pivotal movementbetween the stump unit 12 and the leg unit 14, the leg portion 68 of theactuator bar 66 comes in contact with the cam 70 moving the actuator 66rearwardly which in turn causes the leaf springs 104 to deflect andbecome disassociated from the key slot 56. Upon such an occurrence it isapparent that rotation between the saddle member 20 and the annular ring50 may take place.

The manual release mechanism of the modification shown in FIGS. 59comprises a plunger 112 having a reduced diameter portion 114 freelymounted in a bored boss 116 provided on the knee cap 40. The inner endof the plunger is seated against the end of the actuator 66 in order tomove the actuator inwardly thus moving the portions of the springs 104inwardly out of engagement with the key slot 56. The inner end of theplunger 112 is formed with a transversely extending latch 113 which isoperative to position the portion of the leaf springs 104 extending inthe key slot 56 out of engagement with such slot when the wearerdepresses the plunger 112 inwardly and rotates it 90 so that the latchis seated in a slot 120 formed in the saddle member 20. The relativeposition of the plunger when the latch 118 is seated in the slot 121) isshown in FIG. 9.

Since the material from which the leaf springs 104 are made is rathertough as compared to the annular ring 50, which is preferably made ofTeflon, the leaf springs would cause gouging of the bore of the annularring 50. To prevent such damage, especially when the leaf springs 164are located in the slot by the plunger 112, a generally convex button122 is suitably secured to the inner one of the leaf springs 104.

Thus, it will be seen that a knee joint constructed to incorporate thefeatures shown and described in FIGS. 59, is of a very simplifiedconstruction wherein the elements themselves are easy to manufacture andthey are correlated in a combination having a high degree of reliabilityso that they may perform their intended function over a long period oftime.

I claim:

1. An artificial leg comprising a stump unit and a lower leg assemblyconnected through a swingable knee joint, said knee joint comprising afirst member secured to said stump of said artificial leg, a secondmember rotatably mounted on said first member and secured to said legassembly, lock mean operable between said members to hold them againstrotation, and release means operable after a preselected rearwardswinging movement of said leg assembly relative to said stump wherebysaid lock means holding said first and second members against rotationis released allowing said leg assembly to rotate relative to said stumpunit.

2. The artificial leg as defined in claim 1 wherein the lock meansinclude a lock bar reciprocally mounted on the second member and biasedagainst the first member for locking the engagement, and a key slot insaid first member for receiving said lock bar whereby relative rotationbetween the leg assembly and stump unit is prevented during registeredengagement.

3. An artificial leg which includes a stump unit and a leg unitinterconnected by a knee joint; an externally threaded annular ringsecured to said stump unit, a saddle member having a threaded borethreadedly engaged with said annular ring, a lock bar slidably mountedon said saddle member and located in the bore of said ring member, a keyslot on said annular ring for receiving one end of said lock bar, meansfor urging said lock bar in said key slot, a transverse shaft rotatablysupported by said saddle member, a cam member keyed on said shaft, andmeans operated by said cam member for disengaging said lock bar fromsaid key slot.

4. An artificial leg having a stump unit and a leg assembly connectedthrough a swingable knee joint comprising a pair of relatively rotatablemembers one of which is secured to said stump unit and the other ofwhich is secured to said leg assembly, lock means mounted on one of saidmembers for engagement with the other member for preventing relativerotation between said members, release means operable in response toswingable movements between said stump unit and said leg assembly forreleasing said locking after a preselected swinging movement betweensaid stump unit and said leg assembly and separate release means forreleasing said lock means independent of the relative position of saidstump unit and said leg assembly.

5. A rotatable knee joint interconnecting a leg assembly and a stumpunit of an artificial leg comprising a saddle member rotatablysupporting leg operating linkages, an annular externally threaded ringthreadedly connected in a bore in said saddle member, a key slot in saidannular ring communicating with the bore, lock means resiliently mountedon and extending through said saddle member to engage such key slot insaid annular ring and release means for displacing said lock means fromsaid key slot, thereby freeing said annular ring and said saddle memberfor relative rotation.

6. The structure as defined in claim 5 wherein the lock means includes apair of L-shaped leaf springs secured to and extending through saidsaddle member for engaging the key slot.

References Cited UNITED STATES PATENTS 35,937 7/1862 JeWett 3-191,294,632 2/1919 Dickson 321 X 1,302,336 4/1919 Erickson 3-21 1,376,2924/1921 Sauze 3-25 X 3,273,168 9/1966 Gardner et a1. 32l X RICHARD A.GAUDET, Primary Examiner.

R. L. FRINKS, Assistant Examiner.

1. AN ARTIFICIAL LEG COMPRISING A STUMP UNIT AND A LOWER LEG ASSEMBLYCONNECTED THROUGH A SWINGABLE KNEE JOINT, SAID KNEE JOINT COMPRISING AFIRST MEMBER SECURED TO SAID STUMP OF SAID ARTIFICAL LEG, A SECONDMEMBER ROTATABLY MOUNTED ON SAID FIRST MEMBER AND SECURED TO SAID LEGASSEMBLY, LOCK MEANS OPERABLE BETWEEN SAID MEMBERS TO HOLD THEM AGAINSTROTATION, AND RELEASE MEANS OPERABLE AFTER A PRESELECTED REARWARDSWINGING MOVEMENT OF SAID LEG ASSEMBLY RELATIVE TO SAID STUMP WHEREBYSAID LOCK MEANS HOLDING SAID FIRST AND SECOND MEMBERS AGAINST ROTATIONIS RELEASED ALLOWING SAID LEG ASSEMBLY TO ROTATE RELATIVE TO SAID STUMUNIT.